The present invention relates to the field of steerable medical catheters for insertion into body vessels or cavities which are capable of providing access for surgical and/or medial diagnostic procedures including, but not limited to, providing a conduit for access for fiber optic cables for visualization, lasers, mechanical or electronic devices, surgical devices, or sensors capable of monitoring physiological perimeters in situ, such as pressure transducers, flow probes, oxygen sensors, or sensors for other biological or chemical parameters that might be of clinical relevance.
Instruments of this time having a relatively rigid shaft with a flexible, controllable tip are known. In these prior known instruments, the relatively rigid shaft and flexible tip are made of polymeric materials and are bonded together. Control wires extend through lumens in the shaft and are used to deflect the controllable tip in a desired direction for insertion into a body cavity or vessel. The controllable tip is made of a more flexible polymeric material than the shaft, and may include stabilizing strips encapsulated within the more flexible tip portion of the shaft to control deflection of the tip to a desired direction. However, the stabilizing strips in the flexible tip portion are not connected to the relatively rigid shaft, which places additional stress at the butt joint between the tip portion and the relatively rigid shaft.
It would be desirable to provide a more stable connection between a relatively rigid catheter shaft and a flexible tip portion. It would also be desirable to provide a means for holding a flexible tip in a desired orientation during manipulation of such a steerable medical catheter.
Briefly stated, the present invention provides a steerable medical catheter. The catheter includes a polymeric main shaft having first and second ends with a plurality of lumens extending longitudinally therethrough. A shaft tip portion is provided and includes a metallic coil spring with a polymeric coating having first and second ends. The first end of the metallic coil spring is fused to the second end of the main shaft. The polymeric coating has an inner portion configured to define a plurality of lumens between the first and second ends of the coil spring which extend through the coil spring. The lumens through the coil spring are aligned with the lumens in the main shaft to provide continuous lumens through the catheter. The metallic coil spring is fully encapsulated by the polymeric coating and the second end of the main shaft to which it is fused. A first control wire is located in one of the lumens and has a first end which terminates in proximity to the second end of the coil spring and a second end which extends from the first end of the main shaft.
In another aspect, the shaft tip portion may advantageously include a terminal ring fused to the second end of the shaft tip portion. The first end of the first control wire is permanently affixed to the terminal ring, such as by welding, RF welding, adhesives, or other means. Preferably, an end cap is connected to the terminal ring.
In another aspect of the invention, an outer portion of the polymeric coating on the metallic coil spring has an outside diameter that is approximately equal to an outside diameter of the main shaft. The polymeric coating is fused to the second end of the main shaft around the coil spring to form a sealed connection such that the shaft tip portion forms a continuous, smooth extension of the main shaft. The lumens extending through the main shaft and the tip portion remain isolated from one another to provide a continuous path from the first end of the main shaft to the distal end of the catheter for each lumen.
In another aspect of the invention, a control handle is connected to the first end of the main shaft. The first control wire is connected to a rotatable steering dial located in the control handle such that rotation of the steering dial in a first direction causes the tip portion to flex in a corresponding first direction. The metallic coil spring biases the tip portion to return to a position generally axially aligned with the main shaft when the steering dial is released. Advantageously, a locking device may be provided to hold the steering dial in a desired position.